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.\"     @(#)acct.5	8.1 (Berkeley) 6/5/93
.\"
.Dd February 13, 2017
.Dt ACCT 5
.Os
.Sh NAME
.Nm acct
.Nd execution accounting file
.Sh SYNOPSIS
.In sys/types.h
.In sys/acct.h
.Sh DESCRIPTION
The kernel maintains the following
.Fa acct
information structure for all
processes.
If a process terminates, and accounting is enabled,
the kernel calls the
.Xr acct 2
function call to prepare and append the record
to the accounting file.
.Bd -literal
#define AC_COMM_LEN 16

/*
 * Accounting structure version 3 (current).
 * The first byte is always zero.
 * Time units are microseconds.
 */

struct acctv3 {
	uint8_t  ac_zero;		/* zero identifies new version */
	uint8_t  ac_version;		/* record version number */
	uint16_t ac_len;		/* record length */

	char	  ac_comm[AC_COMM_LEN];	/* command name */
	float	  ac_utime;		/* user time */
	float	  ac_stime;		/* system time */
	float	  ac_etime;		/* elapsed time */
	time_t	  ac_btime;		/* starting time */
	uid_t	  ac_uid;		/* user id */
	gid_t	  ac_gid;		/* group id */
	float	  ac_mem;		/* average memory usage */
	float	  ac_io;		/* count of IO blocks */
	__dev_t   ac_tty;		/* controlling tty */

	uint16_t ac_len2;		/* record length */
	union {
		uint32_t  ac_align;	/* force v1 compatible alignment */

#define	AFORK	0x01			/* forked but not exec'ed */
/* ASU is no longer supported */
#define	ASU	0x02			/* used super-user permissions */
#define	ACOMPAT	0x04			/* used compatibility mode */
#define	ACORE	0x08			/* dumped core */
#define	AXSIG	0x10			/* killed by a signal */
#define ANVER	0x20			/* new record version */

		uint8_t  ac_flag;	/* accounting flags */
	} ac_trailer;

#define ac_flagx ac_trailer.ac_flag
};
.Ed
.Pp
If a terminated process was created by an
.Xr execve 2 ,
the name of the executed file (at most ten characters of it)
is saved in the field
.Fa ac_comm
and its status is saved by setting one of more of the following flags in
.Fa ac_flag :
.Dv AFORK ,
.Dv ACOMPAT ,
.Dv ACORE
and
.Dv ASIG .
.Dv ASU
is no longer supported.
.Dv ANVER
is always set in the above structure.
.Sh SEE ALSO
.Xr lastcomm 1 ,
.Xr acct 2 ,
.Xr execve 2 ,
.Xr sa 8
.Sh HISTORY
A
.Nm
file format appeared in
.At v7 .
The current record format was introduced on May 2007.
It is backwards compatible with the previous format,
which is still documented in
.In sys/acct.h
and supported by
.Xr lastcomm 1
and
.Xr sa 8 .